A recent Guardian series declared it’s “time to talk about geoengineering.” Fine. Let’s talk. And let’s start with some simple truths about these techno-optimistic “quick fixes” that supposedly offset our glacial progress on cutting carbon emissions.
Solar geoengineering proposals - dimming the sun like a celestial dimmer switch - have gotten the most buzz, but they’ve been joined by a whole desperate lineup of schemes to “fix” the climate chaos caused by our carbon dioxide habit. Many threaten polar environments, including the wildly expensive idea of damming the Bering Strait. If implemented, these schemes would put Earth’s climate in a dangerously precarious state and add a major new destabilizing technology to an already turbulent political climate.
Here’s the essential thing: carbon dioxide, once emitted, is only very slowly removed from the atmosphere. A sizable chunk will still be keeping Earth dangerously hot millennia from now. Solar geoengineering, by contrast, involves injecting substances whose effects decay in a matter of years. Some might think that’s an advantage - turn it on and off quickly when the damage becomes clear, right? Wrong.
Recent analyses show it would take as long as two decades to build the required infrastructure. By then, we’d be completely reliant on maintaining it - a tall task in a dangerous world with global conflict. It would only temporarily mask the pent-up warming from ongoing carbon dioxide buildup, and that pent-up warming would be released in a catastrophically rapid “termination shock” if circumstances force the cessation of solar geoengineering. So solar geoengineering doesn’t “buy time” for decarbonisation. The same goes for other geoengineering schemes, which require sustained maintenance over centuries to millennia. Five hundred years from now, the fabled Bering dam may crumble, but the carbon dioxide wreaking havoc on the climate system will still be there waiting.
A lot of unforeseen things can happen in a few decades, let alone centuries. Do we really want to play dice with the planet? Do we want to commit today’s and future generations to maintain these approaches without fail?
Collectively, the four of us - Raymond Pierrehumbert, Julia Slingo, Michael Mann, and Valerie Masson-Delmotte - have studied climate physics for the equivalent of well over 100 years. We know how complex it is and how many surprises it holds. Since 1990, over six assessment reports, the IPCC has worked with tens of thousands of scientists to ensure due diligence on the science and impacts of increasing carbon dioxide. It took over a century of emissions before we could detect climate change and even longer to attribute it unequivocally to humans. It was only in 2015 in Paris that most countries accepted the world is warming and we’re to blame (and 2023 for UNFCCC to mention fossil fuels in a COP outcome).
Now, proponents of geoengineering propose to bash the climate with a whole new hammer - one engaging poorly understood aspects like aerosols, clouds, and regional rainfall patterns. We know this would trigger much more uncertainty, especially with poorly planned, unmanaged, uncoordinated injections of various substances into the high atmosphere, with no governance framework. Surely, we should insist on the same level of scientific diligence as we’ve devoted to understanding the regional consequences of greenhouse gas emissions.
Climate model simulations can indicate what might go wrong but provide no reassurance of what will go right. So far, there’s been no rigorous modelling assessment to explore different solar geoengineering scenarios and no formal intercomparison of the climate’s sensitivity to such interventions, let alone impacts on regional weather and climate variability. What we do know is that the few models used don’t even agree on what level of intervention might be required or what the response will be. After only 10 years of the same stratospheric aerosol injection, global cooling can be anything from less than 10°C to as much as 30°C - a change more rapid than anything we’ve seen from carbon dioxide emissions. We’re essentially flying blind.
The notion that small-scale “safe” experiments can answer important questions about the magnitude and effects of deployment is fundamentally naive. Any meteorologist or oceanographer knows that the massive forces in the global climate system - like the great heat-redistributing currents of the ocean and atmosphere, or year-to-year fluctuations in cloud patterns - will swamp the effects of any experiment and provide no indication of the efficacy and risks of deploying solar geoengineering.
If we’re to seriously consider geoengineering, we need to make sure the scientific foundations are in place. But for the most part, that’s not the kind of research we’re getting in the new tsunami of funding. Instead, we’re getting funding targeted at developing the engineering technology for deployment, regardless of the consequences. The solar geoengineering techno juggernaut rolls on with what seems complete disregard for potential damage to the planet, despite several important assessments from leading scientific academies (to which we belong), including the UK Royal Society, US National Academy, and French Academy of Sciences. Each has highlighted major uncertainties, core ethics, and governance issues, urging great caution.
This is particularly true of the £60m geoengineering programme funded by the UK’s Aria agency. Aria’s chief aim is technology development, and many of its funded geoengineering projects are done in collaboration with for-profit companies. Even more ominous is the explicit entry of venture-capital-funded for-profit startups seeking to make money from solar geoengineering deployment in the near future. The Israeli-US startup Stardust has received more than $60m in venture capital, and their business model assumes near-term deployment. Then there’s Reflect Orbital, which wants to put giant mirrors in low Earth orbit; they’re pitching sales of illumination rather than solar geoengineering, but the technology is identical, and we doubt it will be long before they try to get in on the “cooling credits” game.
All of this is happening in the total absence of governance. There are pious calls for governance from some pro-geoengineering researchers, but what’s the path to get there? Is it governable at all? It’s the height of folly to invest in developing the technology - even if we knew what might work - that only serves to enable unrestricted, profit-motivated deployment by outfits such as Stardust. As private companies whose technology is subject to little regulation, they and their backers have no legal obligations to submit themselves to public scrutiny or provide any assurances on ensuing climate impacts. Will these technologies be carried out devoid of any serious scientific understanding of the consequences and of social, legal, and political concerns?
All of this is a huge diversion of resources and deflection from the task at hand. As one of us likes to say, when you’re in a climate hole, stop digging… and burning fossil fuels. It really is, at some level, that simple.